I'm finding the Aqualarm raw water flow alarm to be a much better idea
in theory than practice. I'm going to call them soon and would be
like to hear any other experiences.

Basically, the calibration seems to drift constantly. I resigned
myself to having to recalibrate it every time I start the engine which
isn't a big deal while I'm waiting for the engine to warm up. I just
set 1000 RPM and push the collar until it just shuts off. That leaves
it set to come on at the water flow corresponding to about 800 RPM
which makes it a nice warning that I'm letting the engine get slow
enough that it might stall during docking.

However, I restart the engine when the wind dies after sailing and the
alarm is going. About half the time I can get it to shut up by
running the RPM briefly up into the cruise range. The rest of the
time, it won't stop beeping until I go down and shove the adjusting
collar to a lower setting. I would think this is my raw water system
draining down and the pump losing its prime except that plenty of
water is coming out the exhaust.

I have a small engine and am using it near the bottom of the unit's
calibration range where it probably isn't as stable. It must work
better with engines 50 hp and up than with my 20 hp Yanmar or it would
have been off the market long ago.

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Roger Long